Drawbench



Nov. 9, 1965 G. A. MITCHELL DRAWBENCH 5 Sheets-Sheet 1 Filed May 17;1963 INVENTOR George A. Mitchell 71/227 ATTORNEY Nov. 9, 1965 s. A.MITCHELL.

DRAWBENCH Filed May 17, 1963 5 Sheets-Sheet 3 INVENTOR.

GEORGE A.MITCHELL Maw Nov. 9, 1965 cs. A. MITCHELL DRAWBENCH 5Sheets-Sheet 4 Filed May 17, 1963 INVENTOR. Q.7M|TCHELL A'I'Tm Nov. 9,1965 s. A. MITCHELL DRAWBENCH 5 Sheets-Sheet 5 Filed May 17, 1963INVENTOR GEORGE AMITCHELL AT;:; N

United States Patent 3,216,234 DRAWBENCH George A. Mitchell, Youngstown,Ohio, assignor to Lombard Corporation, Youngstown, Ohio, a corporationof Ohio Filed May 17, 1963, Ser. No. 281,225 4 Claims. (Cl. 72-288) Thisapplication is a continuation-in-part of copending application SerialNo. 861,388, filed December 22, 1959, now abandoned.

This invention relates to drawbenches of the types having a drawcarriage adapted to pull workpieces, such as tubes, through a die. Moreparticularly, the invention relates to a drawbench wherein the primemover for the draw carriage is a fluid motor.

As is known, a drawbench employs, as a basic component, a circular diethrough which a workpiece is drawn in order to elongate it and reduceits diameter while imparting cold-working properties to the material. Inthe drawing operation, a reduced diameter end of the workpiece isinserted through the die, and this end is engaged by gripper jawscarried on a draw carriage or dolly which travels on a track extendingparallel to the central axis of the die. When the carriage is forcedaway from the die, the workpiece is drawn therethrough. In the casewhere the workpiece is a tube, it is first loaded onto a mandrel locatedon the side of the die opposite the track, and this mandrel forwards areduced diameter end of the tube through the die where it is engaged bythe aforesaid gripper jaws on the draw carriage. As the draw carriagemoves away from the die, the tube is pulled through the annular openingdefined between the periphery of the die and the periphery of themandrel.

In the past, it has been common to pull the draw carriage away from thedie during a drawing operation by the use of chains. In one type ofcommon chain drawbench, the draw carriage is connected to the draw chainor chains by hook devices which automatically retract when the carriageis not under tension. This arrangement is disadvantageous in the case ofcostly alloys where it is desired to stop the drawing operation beforeits completion to examine the progress of the drawn workpiece; and evenif the draw carriage is permanently connected to the chain, expensiveelectrical controls are required for stopping and starting the drivemotor for the chains. Another disadvantage of chain drawbenches is thepulsating pull normally associated with the chain drive due to thearticulation of the chain passing over the drive sprockets. Suchpulsations occur due to variations in the pitch diameter of the sprocketand produce undesirable effects on certain types of materials drawn onthe bench. As the capacity of the bench increases, thus requiring alarger chain, this effect is accentuated.

Still another disadvantage of chain-type benches resides in theirinability to readily vary the speed of the draw carriage during adrawing operation. That is, the chain is driven by electric motors whichrequire extremely complicated and expensive control systems to vary thespeed of the motor. For that matter, many chain-type benches employ adrive motor which operates continually at a constant speed with the drawcarriage being connected to the chains by detachable hook devices.

Many of the disadvantages of chain-type benches can be overcome by usinga hydraulic cylinder as the prime mover. This facilitates an infinitelyvariable draw speed by the use of a variable volume pump driven by aconstant speed motor. In addition, the pulsating pull of chain benchesis eliminated and replaced by a smooth drawing force which can easily beaccelerated, decelerated or stopped during the drawing operation.

Patented Nov. 9, 1965 ice Hydraulic drawbenches, as such, are not new;however most benches of this type employ a cylinder aligned with the dieaxis at the end of the draw carriage track opposite the die, thearrangement being such that the piston within the cylinder pulls thedraw carriage away from the die. This, however, means that the length ofthe cylinder must be approximately equal to that of the track, with theresult that the overall length of the bench is greatly increased. Themaximum draw length established for such benches is about 45 feet, farbelow the maximum for chain-type benches due to various problemsencountered, not the least of which is supporting the piston rod when itis extended out of the cylinder.

The primary object of this invention is to provide a new and improvedhydraulic drawbench arrangement which overcomes the aforementioneddisadvantages of conventional chain and hydraulic drawbenches.

Another object of the invention is to provide a hydraulic drawbenchwherein the hydraulic cylinder employed does not increase the overalllength of the bench.

A further object of the invention is to provide a hydraulic drawbencharrangement wherein the length of the hydraulic cylinder for a givendrawing length can be decreased, thereby minimizing or eliminatingproblems encountered in supporting the piston rod of an extremely longcylinder when it is extended out of the cylinder.

In accordance with the invention, a drawbench is provided wherein thehydraulic cylinder for actuating the draw carriage, instead of being atthe end of the track opposite the die, is located beneath the existingdrawbench structure such that it does not increase the overall length ofthe bench. In one embodiment of the invention, the hydraulic cylinderemploys a ram-type piston which is connected at its forward end to thedraw carriage, the arrangement whereby the stroke of the cylinder iseffecout of the cylinder, it will cause the draw carriage to move awayfrom the die. In another embodiment of the invention, the piston of thehydraulic cylinder located beneath the existing drawbench structure isconnected to the draw carriage through a distance multiplying cablearrangement whereby the stroke of the cylinder is effectively doubled.This means that the cylinder need be .only one half the length of thedraw carriage and, like were limited to a draw length of about 45 feet.

The above and other objects and features of the inverltion will becomeapparent from the following detailed description taken in connectionwith the accompanying drawings which form a part of this specification,and in which:

FIGURE 1 is a top view of one embodiment of the invention;

FIG. 2 is a side view of the drawbench shown in FIG. 1;

FIG. 3 is a cross-sectional view taken along line III-III of FIG. 1showing a supporting frame section for the track structure of thedrawbench shown in FIGS. 1 and 2;

FIG. 4 is an illustration of the hydraulic actuating cylinder for thedrawbench of FIG. 1 and 2, showing its length in comparison with itsdiameter;

FIG. 5 is a cross-sectional view showing the construction of thehydraulic cylinder of FIG. 4;

FIG. 6 is a schematic illustration of the operation of anotherembodiment of the invention wherein the hydraulic actuating cylinder isconnected to the draw carriage of the drawbench through a distancemultiplying cable arrangement;

FIG. 7 is a side schematic view of the drive system shown in FIG. 6;

FIG. 8 is a top view of the drive system shown in FIGS. 6 and 7;

FIG. 9 is a side elevational view of the embodiment of the inventionschematically illustrated in FIGS. 6, 7 and 8;

FIG. 10 is a cross-sectional view taken substantially along line XX ofFIG. 9 showing the arrangement of the sheave carriage and draw carriage;and

FIG. 11 is a schematic illustration of a further embodiment of adistance multiplying arrangement.

Referring to FIG. 1, the numeral 10 designates a die stand having a die12 therein. The die stand 10 is supported on a track assembly, generallyindicated at 14, which extends parallel to the central axis of the dieon one side thereof. The track structure is comprised of a plurality ofspaced frame sections 16, an example of which is shown in FIG. 3. Eachframe section comprises a pair of supporting members 18 and 20 whichextend upwardly from a base 22. The members 18 and 20 areinter-connected by means of a steel plate 24 having an arcuate opening26 provide-d in its central portion. Secured to the periphery of thearcuate opening 26 is a bronze liner or wear strip 28. The wear stripsin the openings 26 of the several frame sections serve to guide andsupport the piston of an actuating hydraulic cylinder, hereinafterdescribed, when it extends along the track structure 14.

Supported on the members 18 and 20 are a pair of tracks or guideways 30and 32 which serve to guide a draw carriage 34 (FIGS. 1 and 2) along apath of travel which is in general alignment with the axis of die 12.The draw carriage 34 is provided with a pair of gripper jaws 36 whichserve to engage the forward end of a tube inserted into the die 12.After the jaws 36 engage the end of a tube, the carriage 34 will bemoved to the left as shown in FIGS. 1 and 2 to thereby pull the tubethrough the die in a manner hereinafter described.

To the right of die stand 10, as shown in FIGS. 1 and 2, is a mandrelsupporting table or structure 38 which comprises an I-beam 40 or thelike structure on a 'plurality of spaced structures 42, substantially asshown. Above the I-beam 40 is a trough 44 which supports the mandrel 46and a tube carried thereby during a drawing operation. The right end ofstruc-- ture 38, as shown in FIGS. 1 and 2, is provided with v a mandrelmanipulating mechanism which comprises a short stroke hydraulic cylinder48 having its piston rod connected to a reciprocable actuating block 50.As shown, the block 50 is provided with a pair of guiding rods 52 and 54slideable within bearings 56 which are welded or otherwise securelyfastened to opposite sides of the I-beam 40. The mandrel 46 is pivotallyconnected to the upper portion of block 50 whereby the mandrel and thetube carried thereby may be moved to the left or right by actuating thecylinder 48. In operation, the cylinder 48 will be initially pressurizedto force the block 50 and mandrel 46 to the right as shown in FIGS. 1and 2. Thereafter, the forward end of the mandrel 46 is elevated to theposition shown in FIG. 2 where a tube from a tube storage rack, notshown, may be threaded onto the mandrel. The forward end of the tube isswaged or reduced in diameter such that when the mandrel is lowered intoa horizontal position, the cylinder 48 may be actuated to move the block50 and the tube-carrying mandrel to the left. In this process the swagedor reduced diameter end of the tube is passed through the apertureformed by the die where it may be engaged by the gripper jaws 36 carriedon draw carriage 34. The draw carriage is then forced to the left asshown in FIGS. 1 and 2 to thereby pull the tube blank through the die.The blank is thereby reduced tothe dimensions of the annular open ingbetween the periphery of the die and the periphery of the enlarged head47 of the mandrel which extends into the die. Although a single mandreland a single die have been shown herein for purposes of simplicity, itshould be understood that a plurality of mandrels and dies may be usedif desired without departing from the scope of the invention. Actually,most drawbenches will incorporate a plurality of dies and mandrelsrather than the single die arrangement illustrated in the drawmgs.

In order to force the draw carriage 34 to the left as shown in FIGS. 1and 2, there is provided a fluid motor (FIGS. 4 and 5) which comprises ahydraulic cylinder 58 having a ram-type piston 60 reciprocable therein.The cylinder 58 is carried by the mandrel supporting structure 38 andhas a length at least equal to the maximum expected length of a tubewhich is to be drawn. In most cases this length will be approximatelyequal to that of the track structure 14 which, incidentally, is longerthan the mandrel supporting structure 38. As the piston 60 movesforwardly out of the cylinder 58, it will pass through successive onesof the bushings 28 in the frame sections 16. Thus, the frame sectionssupport the piston against gravity during a drawing operation.Otherwise, the weight of the piston might cause it to bow downwardlywhile it is in its fully extended position where the draw carriage 34has moved to the left end of track structure 14. The fluid motorcomprised of cylinder 58 and piston 60 is single acting, meaning thatthe piston 60 will move in a power stroke to the left only as shown inFIGS. 1 and 2. Movement of the piston to the left is accomplished byopening surge valve 62 at the right end of cylinder 58 which thenconnects the cylinder to a source of high fluid pressure, not shown. Atthe completion of a drawing operation, the surge, valve 62 is connectedto a low pressure reservoir and means, not shown, such as a continuouschain, return the draw carriage 34 to its initial starting positionwhere the cycle is repeated.

With the arrangement shown in FIGS. 1-3, extremely high drawing forces,on the order of one million pounds or over, can be achieved.Furthermore, the speed of the draw carriage 34 can be made infinitelyvariable by merely regulating the variable volume pumps, not shown,which supply fluid under pressure to the cylinder. Thus, the apparatuscan easily accommodate tubes of various materials which requiredilferent drawing speed. The drawing operation may be stopped and againstarted by merely shutting valve 62 after drawing has initially started.All of the foregoing advantages are, of course, unobtainable inconventional chain-type benches as was explained above.

In FIG. 4 the length of cylinder 58 as compared with its diameter isshown where the length of the cylinder is many times its diameter. Thecylinder is formed from three sections A, B and C which comprisesections of pipe having flanged ends bolted together as at 64 and 66. InFIG. 5 it can be seen that the left end of the cylinder 58 is providedwith a sealing head which comprises a generally annular member 68connected by means of bolts 70 to a flange 72 on section A of thecylinder. The annular member 68 is provided with a circular recess 74which carries a packing ring 76 and annular bushing 78 of bronze or someother similar metal. .The end of annular member 68 is provided with anend plate 80 which is connected to the annular member 68 by means ofbolts 82. A small wiping seal 84 is provided in a recess 85 formed inthe end plate 80, substantially as shown.

The ends of sections A and B which are bolted together at 64 are boredas at 86 and 88 to provide a recess in the inner periphery of thecylinder 58. Received within this recess is an annular bronze bushing90, it being understood that a similar bronze bushing is provided atjunction 66 between sections B and C. Between bushings 90 and annularmember 68 is a second bronze bushing 92 which is slideably positionedwithin the cylinder. This latter bushing does not fit within a recessand has an outer circumference substantially coincident with the innercircumference of the cylinder 58. One or more of the bushings 92 may beprovided between annular member 68 and bushing 90, or between junctions64 and 66. To restrain the bushing 92 against axial movement, a pair ofcylindrical spacers 94 and 96 are provided. These spacers are looselyfitted within the cylinder to permit thermal expansion of the variousparts.

The inner diameters of bushings 78, 90 and 92 are all equal. Thesebushings receive the piston 60 which is a tubular member having circularplugs 98 provided at its opposite ends. When the right end of cylinder58 is pressurized, the piston 60 will be forced to the left as shown inFIG. 2. In so doing, it rides on the inner peripheries of the bushings78, 90, 92, etc. Thus, this piston 60 will make contact with the sidesof the cylinder at spaced points only, these points being at thebushings 78, 90, 92, etc. As will be understood, only the variousbushings 78, 90, 92, etc. need be machined since they are the onlymembers which make contact with the sliding piston 60. Generallyspeaking, the arrangement shown above is practical whenever the lengthof the cylinder is at least thirty times its diameter and can beextended to almost any length within reason.

With reference now to FIGS. 610, another embodiment of the invention isshown which again includes a die stand 100 as well as a draw carriage102 which moves on tracks or guideways toward and away from the diestand 100. When the draw carriage 102 is forced away from the die stand100, it pulls tubes 104 through dies in the stand 100.

In this case, however, the hydraulic actuating cylinder 106 is connectedto the draw carriage through a distance multiplying cable arrangement.In this respect, it will be noted that the piston rod 108 of cylinder106 is connected to a sheave carriage 110 which travels on an I- beamtrack 112 located beneaththe tracks for the draw carriage 102 .at-thebase of the drawbench. Carriedon the sheave carriage 110, as best shownin FIG. 10, are sets of sheaves 114, 116 and 118, 120. As will beunderstood, the carriage 110 and the sheaves carried thereby willreciprocate back and forth along the track 112 when the cylinder 106 ispressurized to move the piston rod 108 in one direction or the other.

Each of the sheaves 114420 is freely rotatable about a common axisextending perpendicular to the longitudinal axes of the dies in dieblocks 100. The sheave carriage 110 is connected to the draw carriage102 through a pair of cables. The one cable, for example, has one endconnected to the drawcarriage at 122. From this point, the cable extendsthrough an upper reach 124 and around a sheave 126 adjacent the dieblock 100 to a lower reach 128. From the lower reach 128 the cablepass-es around the inside sheave 118 and thence to a take-up assembly130. From the take-up assembly 130, the cable passes around the sheave116 on carriage 110: is provided with a lower reach 132 which passesaround a sheave 134 adjacent the die stand 100; and finally is providedwith an upper reach 136 connected to the draw carriage 102 at point 140.

In a somewhat similar manner, a second cable is connected to theopposite end of the draw carriage 102 as at 142 and 144. From point 142,the second cable extends through an upper reach 146, around a sheave 148at the trailing end of the drawbench (see FIGS. 7 and 8); and through alower reach 150 and around the sheave 120 on carriage 110. From thesheave 120 the second cable passes around a second take-up assembly 152and thence around the sheave 114 on carriage 110. From the sheave 114the cable passes through a lower reach 154; around a second sheave 156at the trailing end of 6 the drawbench and through an upper reach 158 tothe point 144.

With the arrangement shown in FIG. 6, movement of the piston rod 108 andthe sheave carriage carried thereby to the right will cause the drawcarriage 102 to move to the left and away from the die stand 100. Thatis, as the carriage 110 moves to the right, the outside sheaves 114 andwill rotate in a counterclockwise direction while the lower reaches and154 are increased in length with the upper reaches 146 and 158 beingdecreased in length. This pulls the draw carriage 102 away from the diestand 100, thereby increasing the length of the upper reaches 124 and136 while decreasing the length of the lower reaches 128 and 132 withthe inner sheaves 116 and 118 rotating in counterclockwise directionsalso.

If the piston 108 and the carriage 110 move fro-m right to left asviewed in FIGS. 6 and 7, the above process is reversed with the sheaves114120 rotating in clockwise directions, the reaches 124 and 126 beingshortened, and the reaches 146 and 158 being increased in length.Tension in the cables is controlled by means of the take-up assemblies130 and 152. That is, the take-up assembly 130 can be drawn toward thedie stand 100 by means of a screw take-up mechanism 160; and, similarly,the takeup assembly 152 can be moved toward the sheaves 148 and 156 bymeans of a screw mechanism 162.

In place 'of the take-up assemblies 130 and 152, the cables on eitherside of the draw carriage 102 could be in two parts with the end of eachpart being anchored in close proximity to the positions of theassemblies 130 and 152. These assemblies, however, provide a convenientmeans for maintaining tension in the cables and, of course, necessitateonly two cable lengths rather than four if each cable is in two parts.

With the arrangement shown, one foot of travel of the sheave carriage110, for example, will cause the draw carriage 102 to move two feet,thereby achieving a two to one distance multiplication. That is, as thesheave carriage 110 moves to the right through a distance of one foot,the lengths of the cable above and below the sheave must each increaseby one foot, with the result that the lengths of reaches 146 and 158 aredecreased in length by two feet. Thus, the length of cylinder 106 needbe only about one half the length of the draw carriage track instead ofthe full length as in the embodiment of FIGS. 1 and 2. Furthermore, thearrangement of FIGS. 6-10 enables the power stroke of the cylinder 106to be a pulling action rather than a pushing action as in FIGS. 1 and 2.That is, since the directions of movement of the draw carriage 102 andthe sheave carriage 110 are always reversed, the draw carriage 102 willmove away from the die stand 100 during a draw ing operation while thepiston rod 108 moves from left to right under tension. This eliminatesthe need for the ram-type piston 60 shown in FIGS. 1 and 2 and theattendant problems involved in maintaining tolerances between the pistonand cylinder.

In order to return the draw carriage 102 tothe die stand 100 at thecompletion of a drawing operation, the piston rod 108 is pushed out ofthe cylinder 106 and is under compression; however at this time verylittle force is required to return the draw carriage 102 with the resultthat there will be very little tendency for the piston rod to buckle.

With reference, now, to FIGS. 9 and 10, the reference numeral representsgenerally the main framework of the drawbench assembly schematicallyillustrated in FIGS. 68 and is comprised of a plurality of spaced framesections 172, as best shown in FIG. 10. The frame sections 172 may befabricated of ordinary structural members welded or otherwise securelyfastened together. Each section includes an upright member 174 and ahorizontally disposed cantilever beam 176 extending outwardly from theupright member or post 174. Depending downwardly from the outer end ofthe cantilever beam 176 is a short beam section 178, which carries atits lower end a track support 180. The support 180 is one of acomplementary pair, a second support 182 being carried by the post 174,as shown.

As will be understood, the complete drawbench assembly incorporates aplurality of frame sections 172, mounted in spaced relation along thelength of the drawbench. Carried by the supports 180 and 182 of suchsections are spaced tracks 184 and 186. The tracks 184 and 186 supportthe draw carriage 102 against gravity and guide it throughout the lengthof the drawbench. On either side of the draw carriage 102 is a secondpair of tracks 188 and 190 in abutment with rollers 192 and 194 carriedon the draw carriage 102. The rollers 192 and 194 are forced outwardlyinto engagement with the tracks 188 and 190 by shock absorbers as ismore fully explained in US. Patent No. 2,861,679. Above the cantileverbeam 176 is a tube storage rack 196, and beneath the rack 196 is aplatform 198 onto which tubes from the storage rack 196 are placedpreparatory to their being loaded onto mandrels in a manner hereinafterdescribed.

Projecting outwardly from the bottom of the supporting post 174 is amember 200 which supports the I-beam track 112. Reciprocable along theI-beam track 112 by means of guide rollers 202 is the sheave carriage110 which carries sheaves 114-120. Above the member 200 and the sheavecarriage 110 is an inclined table 204 onto which tubes drop after beingreleased from the gnipper jaws 206 of the draw carriage 102. When thetubes drop onto the inclined table 204 they will roll into a storage bin206 where they may be picked up by a crane or other suitable device.

With specific reference, now, to FIG. 9, it will be noted that to theright of the main drawbench frame 170 and the die block 100 is a mandreltable 208 which carries a plurality of mandrels 210. The mandrels 210are pivotally anchored at the right end of the mandrel table 208 as at212 and are adapted to be elevated into the position shown by means of ahydraulic or pneumatic cylinder 214. In the drawing operation, tubes tobe drawn on the platform 198 (FIG. 10) are loaded onto the mandrels 210and the cylinder 214 actuated to lower the loaded mandrels such thatthey are axially aligned with the dies in the die block 100. Thereafter,the mandrels 210 are pushed forwardly by means in the mandrel anchoringmechanism 212, not shown, whereby swaged or reduced diameter ends of thetubes on the mandrels 210 are forced through the dies. These reduceddiameter ends are then engaged by the gripper jaws 206 (FIG. '10) on thedraw carriage 102. Thereafter, the cylinder 106 is pressurized to pullthe sheave carriage 110 to the right as viewed in FIG. 9, therebyforcing the draw carriage 102 away from the die stand. In this process,the tubes are drawn through the dies and are reduced in diameter. At theend of the drawing operation when the trailing ends of tubes passthrough the dies, they will jump forwardly with considerable force, theobvious reason being that the tubes are under tension during the drawingoperation and the sudden release of such tension is accompanied by therelease of energy which propels the tubes forwardly. In order to cushionthe impact of the tubes, shock absorbing devices are provided in thedraw carriage 102, a suitable shock absorbing arrangement being shown inthe aforesaid US. Patent No. 2,861,679.

Control of the cylinder 106 and, hence, the draw carriage 102 is bymeans of limit switches spaced along the length of the guideway 112above the sheave carriage 110. The control system may be of the typeshown in copending application Serial No. 101,715. In essence, theopposite ends of the cylinders 106 are connected to the output ports ofa reversible, variable displacement pump which may selectively applyfluid under pressure to either end of the cylinder, and which may beoperated to gradually increase its output pressure in either directionfrom zero up to a maximum limit. Thus, the drawing operation may bestarted gradually rather than abruptly as in the case of a mechanicalbench, and the draw carriage may be easily stopped at any point alongthe draw by reducing the pump output pressure to zero.

With reference now to FIG. 1, still another embodiment of the inventionis shown which is identical in operation to the embodiments of FIGS.6-10, except that a further distance multiplication is achieved. In thiscase, the lower I-beam guideway 112 is replaced by a stationary rack212, while above the stationary rack 212 is a rack 214 which can moveforwardly or backwardly along the drawbench frame on guideways, notshown. The sheave carriage and the sheaves carried thereby are supportedon the rack 214 and reciprocate therewith. Between the gear racks 212and 214 is a gear 216 which meshes with both of the gear racks. The gear216 is connected as shown, to the piston rod 108 of the cylinder 106.From a consideration of the arrangement shown in FIG. 11, it will bereadily appreciated that when the piston rod 108 moves to the rightthrough a distance of one foot, for example, the upper movable gear rack214 will move to the right through two feet. The sheave carriage 110will also move through two feet; while the draw carriage 102 will movethrough four feet in accordance with the explanation given above. Thus,in the arrangement shown in FIG. 11 a four to one distancemultiplication is achieved in contrast to that of FIGS. 6-10.

Although the invention has been shown in connection with certainspecific embodiments, it will be readily apparent to those skilled inthe art that various changes in form and arrangement of parts may bemade to suit requirements without departing from the spirit and scope ofthe invention.

I claim as my invention:

1. In a drawbench including a drawing die, a track structure extendingparallel to the axis of said die on one side thereof, and a drawcarriage movable along said track structure for pulling workpiecesthrough said die; the improvement which comprises a hydraulic cylinderassembly including piston and cylinder elements extending parallel tothe axis of said die, one of said elements being fixed in position andthe other element being movable relative thereto, said fixed elementextending at least partially on the side of the die opposite the trackstructure, a single sheave carriage operatively connected to saidmovable element and mounted for reciprocating movement relative to saidtrack structure, pairs of coaxial sheave devices rotatably carried onopposite sides of said sheave carriage, pairs of sheave devices atopposite ends of said track structure, first cable means having itsopposite ends connected to one end of the draw carriage, said firstcable means passing around one sheave of each pair of sheaves onopposite sides of said sheave carriage as well as around the pair ofsheave devices at one end of the track structure and around a stationarysheave at said one end of the track structure, second cable means havingits opposite ends connected to the other end of the draw carriage, saidsecond cable means passing around one sheave of each pair of sheaves onopposite sides of the sheave carriage, said second cable means alsopassing around the pair of sheaves at the other end of the trackstructure as well as a stationary sheave at said other end of the trackstructure, the arrangement being such that movement of the sheavecarriage in one direction will cause said draw carriage to move in theopposite direction.

2. In a drawbench including a drawing die, a track structure extendingparallel to the axis of said die on one side thereof, and a drawcarriage movable along said track structure for pulling workpiecesthrough said die; the improvement which comprises a hydraulic cylinderassembly including piston and cylinder elements extending parallel tothe axis of said die, one of said elements being fixed in position andthe other element being movable relative thereto, sheave carriage meansoperatively connected to said movable element and mounted forreciprocating movement relative to said track structure, a first pair ofsheave devices rotatably carried on said sheave carriage, a second pairof sheave devices at an end of said track structure, a cable tensioningand take-up assembly positioned at said end of the track structure andinwardly of the second pair of sheave devices, cable means connected toone end of the draw carriage, said cable means having an end connectedto said one end of the draw carriage and extending around a sheavedevice in said second pair, thence around a sheave device in said firstpair, thence to said take-up assembly and around the other sheave devicein said first pair, and finally around the other sheave device in saidsecond pair back to said one end of the draw carriage where it isconnected thereto, and means for selectively drawing said tensioning andtake-up assembly toward said second pair of sheave devices to therebytighten the cable means.

3. The improvement of claim 2 wherein said cable means comprises acontinuous length of cable having its opposite ends connected to saidend of the draw carriage, and wherein said tensioning and take-up deviceincludes a sheave around which the continuous length of cable passes.

4. In a drawbench including a drawing die, a track structure extendingparallel to the axis of said die on one side thereof, and a drawcarriage movable along said track structure for pulling workpiecesthrough said die; the improvement which comprises a hydraulic cylinderassembly including piston and cylinder elements extending parallel tothe axis of said die, one of said elements being fixed in position andthe other element being movable relative thereto, sheave carriage meansoperatively connected to said movable element and mounted forreciprocating movement relative to said track structure, a first pair ofsheave devices rotatably carried on said sheave carriage, a second pairof sheave devices rotatably carried on said sheave carriage, a thirdpair of sheave devices at one end of said track structure, a fourth pairof sheave devices at the other end of said track structure, a firstcable tensioning and take-up assembly positioned at said one end of thetrack structure and inwardly of the third pair of sheave devices, asecond cable tensioning and take-up assembly positioned at said otherend of the track structure and inwardly of the fourth pair of sheavedevices, first cable means connected to said one end of the drawcarriage, said first cable means having an end connected to said one endof the draw carriage and extending around a sheave device in said thirdpair, thence around a sheave device in said first pair, thence to saidfirst take-up assembly and around a sheave device in said first pair,and finally around a sheave device in said third pair back to said oneend of the draw carriage where it is connected thereto, second cablemeans connected to the other end of the draw carriage, said second cablemeans having an end connected to said other end of a draw carriage andextending around a sheave device in said fourth pair, then around asheave device in said second pair, thence to said second take-upassembly and around a sheave device in said second pair, and finallyaround a sheave device in said fourth pair back to said other end of thedraw carriage where it is connected thereto, and means for selectivelydrawing said first and second tensioning and take-up assemblies towardsaid third and fourth pairs of sheave devices repectively to therebytighten the first and second cable means.

References Cited by the Examiner UNITED STATES PATENTS 234,211 11/80Stewart 205-5 897,922 8/08 Noyes et al. 2055 1,870,419 8/32 Palmer 205-7FOREIGN PATENTS 782,636 9/57 Great Britain.

CHARLES W. LANHAM, Primary Examiner.

1. IN A DRAWBENCH INCLUDING A DRAWING DIE, A TRACK STRUCTURE EXTENDINGPARALLEL TO THE AXIS OF SAID DIE ON ONE SIDE THEREOF, AND A DRAWCARRIAGE MOVABLE ALONG SAID TRACK STRUCTURE FOR PULLING WORKPIECESTHROUGH SAID DIE; THE IMPROVEMENT WHICH COMPRISES A HYDRAULIC CYLINDERASSEMBLY INCLUDING PISTON AND CYLINDER ELEMENTS EXTENDING PARALLEL TOTHE AXIS OF SAID DIE, ONE OF SAID ELEMENTS BEING FIXED IN POSITION ANDTHE OTHER ELEMENT BEING MOVABLE RELATIVE THERETO, SAID FIXED ELEMENTEXTENDING AT LEAST PARTIALLY ON THE SIDE OF THE DIE OPPOSITE THE TRACKSTRUCTURE, A SINGLE SHEAVE CARRIAGE OPERATIVELY CONNECTED TO SAIDMOVABLE ELEMENT AND MOUNTED FOR RECIPROCATING MOVEMENT RELATIVE TO SAIDTRACK STRUCTURE, PAIRS OF COAXIAL SHEAVE DEVICES ROTATABLY CARRIED ONOPPOSITE SIDES OF SAID SHEAVE CARRIAGE, PAIRS OF SHEAVE DEVICES ATOPPOSITE ENDS OF SAID TRACK STRUCTURE, FIRST CABLE MEANS HAVING ITSOPPOSITE ENDS CONNECTED TO ONE END OF THE DRAW CARRIAGE, SAID FIRSTCABLE MEANS PASSING AROUND ONE SHEAVE OF EACH PAIR OF SHEAVES ONOPPOSITE SIDES OF SAID SHEAVE CARRIAGE AS WELL AS AROUND THE PAIR OFSHEAVE DEVICES AT ONE END OF THE TRACK STRUCTURE AND AROUND A STATIONARYSHEAVE AT SAID ONE END OF THE TRACK STRUCTURE, SECOND CABLE MEANS HAVINGITS OPPOSITE ENDS CONNECTED TO THE OTHER END OF THE DRAW CARRIAGE, SAIDSECOND CABLE MEANS PASSING AROUND ONE SHEAVE OF EACH PAIR OF SHEAVES ONOPPOSITE SIDES OF THE SHEAVE CARRIAGE, SAID SECOND CABLE MEANS ALSOPASSING AROUND THE PAIR OF SHEAVES AT THE OTHER END OF THE TRACKSTRUCTURE AS WELL AS A STATIONARY SHEAVE AT SAID OTHER END OF THE TRACKSTRUCTURE, THE ARRANGEMENT BEING SUCH THAT MOVEMENT OF THE SHEAVECARRIAGE IN ONE DIRECTION WILL CAUSE SAID DRAW CARRIAGE TO MOVE IN THEOPPOSITE DIRECTION.